Rubber cushioned pads have been in use for years on railway and mine vehicles for cushioning impacts and shocks. Such pads also have been used in suspension systems on trucks and off-highway vehicles. A typical cushioning pad which has given excellent performance is disclosed in D. Willison U.S. Pat. No. 2,686,667, in which the rubber cushion thereof has a corrugated surface. In that patent the ridges in the corrugations are linear and of constant cross-sectional area throughout their length. When a pad of such configuration is compressed, the opposing side faces of the ridges will bulge toward each other and will come into contact first at the midpoint of the ridges and such contact will progressively increase toward the ends of the ridges until the faces are engaged substantially the entire length of the ridges. Once the faces of the ridges are in contact, the valleys are, of course, completely filled and under further loading the cushion will compress as though it were a block or solid body. The load-deflection characteristics of that pad will be such as to produce a stiffer action at light loads than may be desireable for a given type of service.
The present invention is directed to a pad having a resilient cushion of corrugated configuration having alternate ridges and valleys. In the preferred embodiment the sides of the ridges are so contoured that as the cushion is compressed, they will flow inwardly toward each other in such a manner as to come into contact approximately simultaneously over their entire length. In this manner full-length contact between the opposing sides of the ridges is delayed as compared with the pad in the aforementioned patent. Hence, at light loads this pad will provide a larger deflection and, therefore, softer action than the prior art pad. In another form of pad the sides of the ridges may be so contoured as to cause the opposing sides of the ridges to engage at their midpoint shortly after the pad is subjected to a compressive loading. This form of pad results in a stiffer action than the pad having its ridges of constant cross-sectional area and also provides greater deflection at higher load levels.